The biosynthesis of glycoproteins in mineralizing tissues is to be investigated by light microscope and electron microscope radioautography, immunocytochemistry, biochemical analysis and subcellular fractionation. To this end, rats will receive 3H-fucose, 3H-mannose, 3H-glucosamine, 3H-galactose or 35S-sulfate intravenously. Some animals will receive cycloheximide prior to injection. Incisor teeth and surrounding bone will be processed after fixation, and labeled precursors will be traced in odontoblasts, osteoblasts and ameloblasts. Intracellular sites of uptake, pathways of migration, the mode of discharge and patterns of deposition of glycoproteins into each matrix will be explored. Reduced ameloblasts, dental cuticle, subsurface enamel matrix and the epithelial attachment will also be examined. Collagen biosynthesis will be traced in osteoblasts of chick embryo calvaria by combined radioautographic and biochemical studies utilizing 3H-proline. The organelle(s) in which procollagen peptides aggregate during transport and secretion will be identified. Other glycoproteins, glycosaminoglycans, and phosphoproteins will be similarly examined. The endoplasmic reticulum, Golgi apparatus and secretory granules of osteoblasts and odontoblasts will be isolated in order to define their roles in the synthesis of collagen and other glycoproteins, as well as to determine kinetics of transport. The intracellular distribution of procollagen will be examined by immunocytochemistry. Thus, it is hoped to elucidate the steps involved in the elaboration of matrix glycoproteins, and to determine their roles in the development of calcifying matrices.